Yamaha Mx124 Instruction Manual

							MIXING CONSOLE
Owner’s Manual
Thank you for purchasing the YAMAHA MX12/6 or MX20/6 Mixing Con-
sole. Both the MX12/6 and MX20/6 mixers are designed to provide the user
with an ideal balance of operability, functionality, and simplicity.
In order to get the most out of your MX12/6 or MX20/6 mixer and its
functions, and to enjoy years of trouble-free use, please read this Owner’s
Manual thoroughly and keep it in a safe place for future reference.
Features
• The MX12/6 offers 12 input channels that can be mixed into
stereo, monaural, or to four group outputs.
• The MX20/6 offers 20 input channels that can be mixed into
stereo, monaural, or to four group outputs.
• A C-R/PHONES jack offers easy connection to a sub amp for
monitoring. It allows monitoring of the main stereo output,
TAPE IN input and the signals from groups 1/2, 3/4.
• The mixer is equipped with a highly efficient, built-in digital
effects section. The built-in effects allow you to create
professional sounding mixes without the need of additional
equipment. An EFFECT SEND jack is also supplied to allow
the use of external effectors.
• Two AUX SEND/RETURN jacks are provided. Two separate
AUX buses can be used as sends for external effectors or a
monitor system.
• The mixer supplies phantom power to provide easy connec-
tion of condenser microphones that require an external
power source.
• The mixer is equipped with INSERT I/O jacks for input
channels 1-4 (MX12/6) or 1-8 (MX20/6) allowing individual
effects to be inserted into individual channels.
• Both XLR type mic input jacks and TRS phone line input
jacks are provided on channels 1-8 (MX12/6) or 1-16 (MX20/
6). Input channels 9-12 (MX12/6) or 17-20 (MX20/6) are
equipped with stereo line input jacks. The MX12/6 and
MX20/6 can handle a wide range of sources, from micro-
phones to line level devices and stereo output synthesizers.
• TAPE IN jacks and REC OUT jacks offer easy connection of
tape decks for playback and recording.
Contents
Front & Rear Panels............................ 2
Channel Control Section ........................ 2
Master Control Section .......................... 4
Connector Section ................................. 6
Rear Panel ............................................. 7
Applications............................................ 9
Supplement.......................................... 11
Specifications ....................................... 11
Dimensions .......................................... 12
Block and Level Diagrams .................... 13
Keep This Manual For Future Reference. 
						

							MX12/6, 20/6 — Owner’s Manual
FCC INFORMATION (U.S.A.)
1. IMPORTANT NOTICE: DO NOT MODIFY THIS UNIT! This product, when installed as indicated in the instructions contained in this manual, meets FCC 
requirements. Modifications not expressly approved by Yamaha may void your authority, granted by the FCC, to use the product.
2. IMPORTANT: When connecting this product to accessories and/or another product use only high quality shielded cables. Cable/s supplied with this product MUST 
be used. Follow all installation instructions. Failure to follow instructions could void your FCC authorization to use this product in the USA.
3. NOTE: This product has been tested and found to comply with the requirements listed in FCC Regulations, Part 15 for Class “B” digital devices. Compliance with 
these requirements provides a reasonable level of assurance that your use of this product in a residential environment will not result in harmful interference with 
other electronic devices. This equipment generates/uses radio frequencies and, if not installed and used according to the instructions found in the users manual, may 
cause interference harmful to the operation of other electronic devices. Compliance with FCC regulations does not guarantee that interference will not occur in all 
installations. If this product is found to be the source of interference, which can be determined by turning the unit “OFF” and “ON”, please try to eliminate the 
problem by using one of the following measures: Relocate either this product or the device that is being affected by the interference. Utilize power outlets that are on 
different branch (circuit breaker or fuse) circuits or install AC line filter/s. In the case of radio or TV interference, relocate/reorient the antenna. If the antenna lead-in 
is 300 ohm ribbon lead, change the lead-in to coaxial type cable. If these corrective measures do not produce satisfactory results, please contact the local retailer 
authorized to distribute this type of product. If you can not locate the appropriate retailer, please contact Yamaha Corporation of America, Electronic Service 
Division, 6600 Orangethorpe Ave, Buena Park, CA 90620
The above statements apply ONLY to those products distributed by Yamaha Corporation of America or its subsidiaries.
WARNING: THIS APPARATUS MUST BE EARTHED
IMPORTANT
THE WIRES IN THIS MAINS LEAD ARE COLOURED IN 
ACCORDANCE WITH THE FOLLOWING CODE:
          GREEN-AND-YELLOW :      EARTH
          BLUE :                                     NEUTRAL
          BROWN :                                LIVE
As the colours of the wires in the mains lead of this apparatus may 
not correspond with the coloured markings identifying the terminals in 
your plug, proceed as follows:
The wire which is coloured GREEN and YELLOW must be 
connected to the terminal in the plug which is marked by the letter E 
or by the safety earth symbol        or coloured GREEN and YELLOW.
The wire which is coloured BLUE must be connected to the terminal 
which is marked with the letter N or coloured BLACK.
The wire which is coloured BROWN must be connected to the 
terminal which is marked with the letter L or coloured RED.
* This applies only to products distributed by YAMAHA KEMBLE 
MUSIC (U.K.) LTD. 
						

							MX12/6, 20/6 — Owner’s Manual
Important
Read the following before operating the MX12/6, 20/6
Important1
Warnings
• Do not place a container with liquid or small metal objects on top of this unit. Liquid or metal objects
inside this unit are a fire and electrical shock hazard.
• Do not allow water to enter this unit or allow the unit to become wet. Fire or electrical shock may result.
• Connect this unit’s power cord only to an AC outlet of the type stated in this Owner’s Manual or as
marked on the unit. Failure to do so is a fire and electrical shock hazard.
• Do not scratch, bend, twist, pull, or heat the power cord. A damaged power cord is a fire and electrical
shock hazard.
• Do not place heavy objects, including this unit, on top of the power cord. A damaged power cord is a fire
and electrical shock hazard. In particular, be careful not to place heavy objects on a power cord covered
by a carpet.
• If you notice any abnormality, such as smoke, odor, or noise, or if a foreign object or liquid gets inside
the unit, turn it off immediately. Remove the power cord from the AC outlet. Consult your dealer for
repair. Using the unit in this condition is a fire and electrical shock hazard.
• Should this unit be dropped or the cabinet be damaged, turn the power switch off, remove the power
plug from the AC outlet, and contact your dealer. If you continue using the unit without heeding this
instruction, fire or electrical shock may result.
• If the power cord is damaged (i.e., cut or a bare wire is exposed), ask your dealer for a replacement. Using
the unit with a damaged power cord is a fire and electrical shock hazard.
• Do not remove the unit’s cover. You could receive an electrical shock. If you think internal inspection,
maintenance, or repair is necessary, contact your dealer.
• Do not modify the unit. Doing so is a fire and electrical shock hazard.
• If lightning begins to occur, turn off the power switch of the unit as soon as possible, and unplug the
power cable plug from the electrical outlet.
• If there is a possibility of lightning, do not touch the power cable plug if it is still connected. Doing so
may be an electrical shock hazard.
Cautions
• Hold the power cord plug when disconnecting it from an AC outlet. Never pull the cord. A damaged
power cord is a potential fire and electrical shock hazard.
• Do not touch the power plug with wet hands. Doing so is a potential electrical shock hazard.
Operating Notes
• Using a mobile telephone near this unit may induce noise. If noise occurs, use the telephone away from
the unit.
• XLR-type connectors are wired as follows:
pin 1: ground, pin 2: hot (+), and pin 3: cold (-).
• Insert TRS phone jacks are wired as follows: sleeve: ground, tip: send, and ring: return.
• The performance of components with moving contacts, such switches, rotary controls, faders, and
connectors, deteriorates over time. The rate of deterioration depends on the operating environment and
is unavoidable. Consult your dealer about replacing defective components. 
						

							MX12/6, 20/6 — Owner’s Manual
2Front & Rear Panels
q
y t
o
u
e
iit r r
w
The MX12/6’s panel is used for all following
illustrations in this manual.
Channels
1-8 (MX12/6)
1-16 (MX20/6)
(Monaural)Channels
9-12 (MX12/6)
17-20 (MX20/6)
(Stereo)
Response [dB]
+5 +10 +15
–15 –10 –5 0
Frequency [Hz]10k 1k 100 20k 20 +20
–20
Front & Rear Panels
Channel Control Section
qGAIN Control
Adjusts the input level of the signal entering the mixer to an
optimum level.
To obtain an optimum balance between the S/N ratio and
dynamic range, adjust the level so that the peak indicator w
occasionally lights.
-60 to -16 indicates the MIC input adjustment level, -34 to +10
indicates the LINE input adjustment level.
wPEAK Indicator
The indicator detects peaks in the signal after it has passed the
EQ.
The indicator will light red when the level reaches +17dB to
warn that clipping is imminent.
eEqualizer
Provides +/-15dB of control over high, mid and low frequency
ranges at the center frequencies listed below.
HIGH : 10kHz (shelving)
MID : 2.5 kHz (peaking)
LOW : 100Hz (shelving)
Frequency response will be flat when the knob is positioned at
“G”.
rAUX1, AUX2 Controls
tPOST Switch
Individually controls the level of the signal sent from each
channel to the AUX1 and AUX2 buses.
The signal taken from before the channel fader is sent to
AUX1.
Depending upon the POST switch setting, the signal taken
from either before (POST Switch = ?) or after (POST Switch
= >) the channel fader is sent to AUX2.
When a stereo channel is used, L and R signals are combined
and sent to the AUX1 and AUX2 buses. 
						

							MX12/6, 20/6 — Owner’s Manual
yEFFECT Control
Controls the level of the signal sent from each channel to the EFFECT bus.
This control is located after the channel fader so its level will also be affected by the channel fader
setting.
When a stereo channel is used, L and R channel signals are combined and sent to the EFFECT bus.
uPAN Control (MX12/6:CH1-8, MX20/6:CH1-16)
BAL Control (MX12/6:CH9-12, MX20/6:CH17-20)
The PAN control knobs set the position within the stereo field of each signal that is sent to the GROUP
bus 1-2, GROUP bus 3-4 and STEREO bus L-R.
The BAL control knobs set the balance between left and right channels and assigns the signals that are
received at INPUT L (MX12/6:CH9, 11, MX20/6:CH17, 19) to GROUP buses 1/3 or STEREO bus L,
and the signals received at INPUT R (MX12/6:CH10, 12, MX20/6:CH18, 20) to GROUP buses 2/4 or
STEREO bus R.
iGROUP, ST Select Switches
Used to send the signal of each channel to the GROUP bus 1-2, GROUP bus 3-4 and STEREO bus L-R.
When the switch is ON (>), the signal is sent to the relative bus.
oChannel Fader
Controls the output level of the input channel signal and adjusts the volume balance between channels.
* Levels of unused faders should be lowered.
Front & Rear Panels3
CH INPUTMX12/6:1~4ch
MX20/6:1~8ch
MIC INPUT[-60~-16dB]
LINE INPUT[-34~+10dB]
INSERT I/O[0dB]
PADPHANTOM
(8ch/sw)from DC Power Supply
HA
GAIN
[-60dB~-16dB]
[-34dB~+10dB][0dB]Lo
Mid
Hi
3-Stage EQ
PEAK
Ch.Fader[-10dB]
BA[0dB][0dB]
1-2
3-4
ST
[-6dB]PAN
POSTAUX1
AUX2
EFFECT
CH INPUT
MX12/6:5~8ch
MX20/6:9~16ch
MIC INPUT[-60~-16dB]
LINE INPUT[-34~+10dB]from DC Power Supply
PHANTOM(8ch/sw)
PADHA
GAIN[-60dB~-16dB]
[-34dB~+10dB][0dB]Lo
Mid
Hi
3-Stage EQ
PEAK
Ch.Fader[-10dB]
BA[0dB][0dB]
1-2
3-4
ST
[-6dB]PAN
POSTAUX1
AUX2
EFFECT
ST INPUT
MX12/6: 9/10ch, 11/12ch
MX20/6:17/18ch, 19/20ch
[-34~+10dB]
L
RHA
HA
[0dB]
GAIN[-34dB~+10dB]
3-Stage EQ
Lo
Mid
Hi
3-Stage EQ
PEAK
BABA
ST Ch.Fader
[-10dB][0dB]
SUMBAL
[0dB]
POST
1-2
3-4
ST
[-6dB]
AUX1
AUX2
EFFECT
STEREO R
EFFECTSTEREO L GROUP4 GROUP3GROUP2 GROUP1
AUX1
AUX2 
						

							MX12/6, 20/6 — Owner’s Manual
4Front & Rear Panels
q !2
!0
er
i
w
!1 !3!4
o
ty
uqST Master Fader
Controls the level of the signal that is sent to the ST
OUT jacks.
wMONO Control
Controls the level of the signal (the monaural signal
that is formed by combining the signals from the
STEREO bus) that is sent to the MONO OUT jack.
eGROUP 1-4 Faders
rTO ST Switch
Controls the level of the GROUP 1-4 signals, and
sends the signals to their respective GROUP
OUTPUT 1-4 jacks.
Also, when the TO ST switch is ON (>), the signals
whose levels are controlled by the GROUP faders are
also sent to the STEREO bus.
tSEND
• AUX1, AUX2 Controls
Controls the individual levels of the AUX1 and
AUX2 signals that are sent to the AUX1 SEND
jack and AUX2 SEND jack.
• EFFECT Control
Controls the level of the EFFECT bus signal that
is sent to the EFFECT SEND jack.
* This control is not related to, and has no affect on the
signal that is sent from the EFFECT bus to the built-in
digital effects.
yRETURN
• AUX1, AUX2 Controls
Controls the levels of the signals (mixed, L with
R) that are sent to the AUX1 and AUX2 buses
from the RETURN L (MONO) and R jacks.
• ST Control
Controls the level of the signal that is sent from
the RETURN L(MONO), R jacks to the STEREO
bus.
* When only the RETURN L (MONO) jack is used, the
same signal is also sent to the STEREO bus L, R.
Master Control Section 
						

							MX12/6, 20/6 — Owner’s Manual
Front & Rear Panels5
uDIGITAL EFFECT
• PROGRAM Select Switch
Selects a program from the built-in digital effects.
VOCAL ECHO 1
VOCAL ECHO 2
VOCAL ECHO 3
VOCAL ECHO 4
VOCAL REVERB 1
VOCAL REVERB 2
VOCAL REVERB 3
VOCAL REVERB 4
• PARAMETER Control
Controls parameters (effect level, speed, etc.) of the selected effect program.
• ON Switch
Switches the built-in digital effect ON (>) or OFF (?). When set to OFF, the signal from the built-
in effect is not sent.
• AUX1, AUX2 Control
Controls the level of the signal that is sent from the built-in digital effects to the AUX1 and AUX2
buses.
• ST Control
Controls the level of the signal that is sent from the built-in digital effects to the STEREO bus.
iTAPE IN Control
Controls the level of the signal that is sent from the TAPE IN jack to the STEREO bus.
oST GRAPHIC EQUALIZER
A stereo 7-band graphic equalizer that offers tone adjustment to the signal that is output to the ST OUT
jacks.
A +/-12dB boost or cut is provided at each of the frequency bands 125, 250, 500, 1k, 2k, 4k and 8kHz.
!0C-R/PHONES Output and Meter Select Switch
Selects the signal that is sent to the C-R/PHONES jack and the level meter.
The three switches are used in combination to select TAPE IN, ST, GROUP 1-2 and GROUP 3-4 signals.
HALL 1
HALL 2
HALL 3
ROOM
PLATE 1
PLATE 2
PLATE 3
GATE REVERB
SignalSwitch? 1-2      > 3-4? ST      > GROUP?      > TAPE  IN
TAPE INN/A N/A> TAPE IN
STN/A? ST?
GROUP 1-2? 1-2> GROUP?
GROUP 3-4> 3-4> GROUP?
!1C-R/PHONES Control
Controls the level of the signal that is sent to the C-R/PHONES jack.
!2LEVEL Meter
The LEDs indicate the output level of the signal selected with the C-R/PHONES output and Meter
Select Switch !0 . “0” indicates a nominal level, and the PEAK indicator will light when clipping is
imminent.
!3POWER Indicator
The indicator will light when the main unit’s power is ON.
!4LAMP Connector
A BNC type lamp (AC or DC12V, 0.5A Max) can be attached here.
Refer to the Block Diagram on page 13. 
						

							MX12/6, 20/6 — Owner’s Manual
6Front & Rear Panels
qwrte
qINPUT Jacks (MX12/6:CH1-8, MX20/6:CH1-16)
• MICBalanced XLR type microphone input jacks (1:Ground, 2:Hot, 3:Cold).
These input jacks are compatible with 50-600Ω microphones.
• LINEBalanced TRS phone type line input jacks (T:Hot, R:Cold, S:Ground).
These input jacks are compatible with 600Ω line level devices.
Unbalanced phone plugs can be connected but noise may enter the signal if the cables are
too long or if the location is susceptible to electromagnetic interference.
Connector Section
NOTE:   It is not possible to simultaneously use both the MIC INPUT jack and the LINE INPUT
jack on any individual channel. Please use only one or the other jack.
wINPUT Jacks (MX12/6:CH9-12, MX20/6:CH17-20)
Unbalanced phone type and RCA pin type stereo line input jacks.
These inputs are compatible with 600Ω line level devices.
NOTE:   It is not possible to simultaneously use both the phone type and RCA pin type jacks for an
individual input channel. Please use only one or the other jack.
eST OUT (L, R) Jacks
Balanced XLR type output jacks with a nominal output/impedance of +4dB/600Ω.
These jacks deliver stereo output of the mixed signal and are connected to a power amplifier, etc. that
drives the main speakers.
The outputs can also be used for recording with the level of the signal controlled by the ST Master
Fader.
rMONO OUT Jack
Balanced XLR type output jack with a nominal output/impedance of +4dB/600Ω.
This signal is the monaural mix of the STEREO bus’s stereo signal. Its level is controlled with the
MONO control.
tC-R/PHONES Jack
Stereo phone type output jack for connecting a set of headphones (nominal output/impedance of
3mW/40Ω).
It can also be used as a stereo phone type output jack for connecting a monitor system (nominal
output/impedance of +4dB/10kΩ).
The source that is monitored with this jack is selected with the C-R/PHONES Output and Meter Select
Switch (Master Control Section).
NOTE:   When this jack is connected to a monitor system, an insertion cable (optional YAMAHA
insertion cable YIC025/050/070, etc.) may be used. (Tip:L, Ring:R, Sleeve:Ground) 
						

							MX12/6, 20/6 — Owner’s Manual
Front & Rear Panels7
qINSERT I/O Jack (MX12/6:CH1-4, MX20/6:CH1-8)
These are input/output jacks that are positioned
between the equalizer and fader of the input
channel.
They have a nominal input/impedance of 0dB/
600Ω and a nominal output/impedance of 0dB/
10kΩ.
These jacks can be used to connect devices such
as a graphic equalizer, compressor, noise filter,
etc.
The TRS type phone jack allows bi-directional
connection with the INSERT I/O jack. Connect-
ing a device to these jacks will require a special
insertion cable like the one shown in the diagram
on the right. Please use an optional YAMAHA
Insertion Cable YIC025/050/070, etc.
wPHANTOM  +48V Switch
Turns the phantom power ON/OFF for all channels 1-8.
The MX20/6 has an additional PHANTOM switch for channels 9-16.
Turn the switch ON when you are using condenser microphones, etc.
When the switch is ON, +48V DC is supplied to pins 2 and 3 of the XLR type MIC INPUT connectors.
If phantom power is not required, make sure the switch is set to the OFF position.
Rear Panel
q e r t yw
u i
to the INSERT I/O
jackto the input jack of
the external processor
to the output jack of
the external processor
Tip Sleeve
Ring
TipSleeve
NOTE:   With this switch turned ON, it is not a problem to connect balanced dynamic microphones
or line level devices however, hum or malfunction may occur when connecting unbalanced devices
or devices for which the center of the transformer is ungrounded.
eSEND Jack
• AUX1, AUX2
These are impedance balanced phone type output jacks with a nominal output/impedance of +4dB/
600Ω.
The AUX1, 2 bus signals are output from their respective jacks. The jacks can be used to send the
signal to a monitor system such as a cue-box. 
						

							MX12/6, 20/6 — Owner’s Manual
8Front & Rear Panels
• EFFECT
This is an impedance balanced phone type output jack with a nominal output/impedance of +4dB/
600Ω.
The EFFECT bus signal is sent from this jack. This jack is used to send the signal to an external
effector, etc.
rRETURN L (MONO), R Jacks
These are unbalanced phone type line input jacks with a nominal input/impedance of +4dB/600Ω.
The signal received by these jacks is sent to the STEREO bus, AUX1 and AUX2 buses.
These jacks are normally used to receive a return signal from an external effector such as reverb, delay,
etc., but they can also be used as an auxiliary stereo input. If only the L (MONO) jack is used, the same
signal will be sent to both the R and L jacks for monaural input.
tGROUP OUT (1-4) Jacks
These are impedance balanced phone type output jacks that deliver the GROUP bus 1-4 signals, with a
nominal output/impedance of +4dB/600Ω.
These jacks are normally connected to the input jacks on an MTR or external mixer.
yTAPE IN (L, R) Jacks
These are line input jacks for monitoring an external DAT recorder or CD player. The signal received by
these jacks is sent to the STEREO bus. In this case, the TAPE IN control is used to adjust the input level
of the signal. You can also monitor directly from the C-R/ PHONES jack by making the appropriate
selection with the C-R/PHONES Output and Meter Select Switch (Master Control Section).
uREC OUT (L, R) Jacks
With an external DAT recorder or cassette recorder connected to these jacks, you can record the same
signal that is sent from the ST OUT jacks.
The signal sent from these jacks is not affected by the ST Master Fader or Graphic EQ settings. Make
recording level adjustments on the recording device.
iPOWER Switch
When the switch is in the ON position, the unit is powered.
When turning the power ON, first turn on the mixing console, then turn on the power amp or powered
speakers that are connected to the mixer.
Also, when turning the power OFF, turn off the power amp or powered speakers before turning off the
mixing console.
Connector polarity
MIC INPUT, ST OUT,
MONO OUTPin 1: ground
Pin 2: hot (+)
Pin 3: cold (–)
LINE INPUT, GROUP OUT,
AUX 1/AUX 2/EFFECT SENDTip: hot (+)
Ring: cold (–)
Sleeve: ground
INSERT I/OTip: Output
Ring: Input
Sleeve: ground
C-R/PHONESTip: L
Ring: R
Sleeve: ground
STEREO INPUT, RETURN
Tip SleeveRing
Tip Sleeve
Tip: hot
Sleeve: groundINPUT OUTPUT